They then headed to Downing Street where Mrs McCourt’s Helen’s law petition, which has been signed by 320,000 people, was delivered to Prime Minister David Cameron.

Mr McGinn said: “Marie made her case with characteristic decency and dignity. She is an extraordinary woman who despite enduring the most awful suffering is dedicated to helping others.

“The Victims Minister listened carefully and responded positively.

“The priority for me now is to ensure that the Secretary of State for Justice is fully informed of all the facts around Helen McCourt’s case before making the final decision about whether her murderer is to be transferred to an open prison.

“I also welcome the fact that the Prisons Minister has responded to the overwhelming public support for our campaign to introduce Helen’s Law, and has asked the parole board to review the guidelines around convicted murderers who refuse to reveal the location of their victims’ remains.

“I want to see immediate progress on this and I will be keeping the pressure on the Government so that victims and their families get the justice they deserve.”